A medication dispenser with compliance monitoring capability should optimally offer both single dose accuracy and accommodation of standard (as currently marketed) medication packaging. Previous designs typically either adopt a standard medication package and forsake monitoring single dose dispensing or they implement non-standard medication storage and more complicated mechanisms to provide single dose monitoring and/or single dose access control.
Pill bottle caps, as represented by the device disclosed in U.S. Pat. No. 4,939,705 of Hamilton et al. function with standard bottle packaging but allow access to the bulk medication supply during each dispensing event. Once the device recognizes the removal of the cap, any number of doses may be removed from the bottle without proper recognition, thus seriously compromising the device's ability to properly record the dosing intervals. Even more troublesome is the possibility that the cap device might not be reinstalled on the bottle; if not, then subsequent removals of medication from the bottle go unmonitored.
Dispensers described in U.S. Pat. No. 4,717,042 of McLaughlin and U.S. Pat. No. 4,572,403 of Benaroya are representative of the more complicated devices that address the issue of single dose control by requiring that the medication be placed in non-standard cellular structures and use electromechanical devices in order to control access to and monitor dispensing of a single dose of medication. The significant extra device cost due to the use of solenoids, motors, and the like, and the labor cost incurred in having to have a pharmacist or caregiver load the custom container is a serious disadvantage in an increasingly cost sensitive marketplace such as healthcare. The special loading required by this class of devices also represents additional potential for dosing errors.
The monitoring devices disclosed in U.S. Pat. No. 4,971,221 of Urquhart et al. and in U.S. Pat. No. 4,616,316 of Hanpeter et al. address the need for using more standard packaging and single dose monitoring but suffer from other disadvantages. The device of Urquhart et al. can be built around a standard blister package and monitors ejection of a medication from the package with a photo-interrupter. Because the optical sensing system must be energized at the instant the medication passes through the sensing passageway and because the sensor requires too much power for continuous battery powered operation, a dispenser access cover and opening/closing monitoring circuitry is required in order to control and conserve sensor power and to prevent false indications from objects entering the output end of the sensor passageway between true dispensing events. If the access cover is left open after dispensing a medication, the battery conservation feature is defeated, and inadvertent insertion of objects into the sensing passageway can cause dispensing data errors.
In the U.S. Pat. No. 4,616,316 device of Hanpeter et al., blister packaging technology is modified by the addition of a circuit layer to the package backing layer. As medication is pushed through the modified backing layer, a circuit is broken and a signal is communicated to the supervisory electronics through a connector attached to the circuit layer. Although this construction allows each dose removal to be monitored, standard blister packages as supplied by the pharmaceutical manufacturer are not accommodated. Rather, custom packaging with the disclosed modifications is required. Fabrication of the non-standard blister packages must include the addition of circuit layer and connector elements. Revised tooling to construct this unique package would represent a major investment and each drug so packaged would require expensive and time consuming testing for migration or leakage of foreign materials or solvents into the package. Based on these results the new package might or might not receive approval by appropriate regulatory authorities. The circuit layer and connector components add expense to what is necessarily a disposable package. Further, pharmacies would have the additional expense and inconvenience of stocking an additional presentation of the medication for use when prescribed with the dispensing device. Also, the attachment of the conductive traces directly to the backing of the medication package presents a concern whether the traces or the adhesive used to attach the traces will leach through the package and into the medication.
The Hanpeter device is intended for use in the research setting and is not appropriate for consumer use. Aligning and inserting the multi-pole connector on the modified blister package into a socket in the dispenser could represent a difficult task if performed by the patient and would contribute to installation errors during refilling and poorer reliability during operation.
It is this inadequacy of existing devices to simply and economically combine good accuracy with standard packaging, that is addressed by this invention. Use of standard packaging, as presently marketed, would make such devices more convenient and less expensive for all: patient, pharmacist, and pharmaceutical manufacturer. Uncomplicated unit dose dispensing sensitivity that conserves operating power would make such monitored dispensers more accurate, convenient to use, and economical.